Tuning headroom and reversible tunes (JB4, Dinan, flash)

The S55 responds strongly to tuning, from plug-and-play JB4 piggybacks (roughly 20+ HP, toggled off from a phone) to reflashable Carbahn/BM3/MHD tunes and Dinan Stage 2 packages that push into the mid-500s while, in Dinan's case, retaining full factory warranty—and most tunes can be returned to stock, a point buyers probe as due diligence.